I think the problem with the original Genesis was that many vendors didn't like it being androgynous and there was a lot of talk about it being difficult to develop for. I found that surprising as Genesis was the first figure I found easy to develop for and made a number of things for Genesis. Many of which I never got around to releasing.
However once Genesis 2 was split into the two sexes there were a number of vendors who came on board that previously hadn't been willing to. Genesis 3 has seen more vendors coming over to making for the daz figures again but I'm not sure if that's due to the figures or Iray. There are a lot of people who've posted how they like Iray.
I think that there are a number of variables as to why people develop now for DS when they used to develop for Poser. I don't believe that it is one specific thing.
However once Genesis 2 was split into the two sexes there were a number of vendors who came on board that previously hadn't been willing to. Genesis 3 has seen more vendors coming over to making for the daz figures again but I'm not sure if that's due to the figures or Iray. There are a lot of people who've posted how they like Iray.
I think that there are a number of variables as to why people develop now for DS when they used to develop for Poser. I don't believe that it is one specific thing.